The present invention relates to vehicle door latches, and more particularly to vehicle door latches having power-assisted unlatching.
Power unlatching is by now fairly well-established, having been used for several years on luxury and sport vehicles. The power unlatching mechanism typically includes a motor-operated linkage that acts on the fork bolt detent, causing the detent to disengage the fork bolt and allow the fork bolt to rotate from a latched position to an unlatched position. The mechanism also includes an exposed door switch that allows a person to effect unlatching simply by manipulating the switch.
This power unlatching has the advantage that a person can lock the latch simply by interrupting power. If there is no power supply, the latch cannot unlatch even if a person attempts to operate the switch. Child security is similarly easy to effect because the driver can simply interrupt power to the rear inside door switch, and thereby prevent a child seated in the rear seat from unlatching the latch through manipulation of the switch.
The challenge for these systems is to find a suitable way to provide manual door unlatching in the event of a power failure. Various ways have already been devised. In one case, the doors have inside latch handles with a given amount of travel. The power unlatching switch is associated with the handle such that the switch can be manipulatedxe2x80x94and the latch unlatchedxe2x80x94when someone pulls the handle through the first portion of its travel. If the vehicle""s power is functioning, a person can thus effect power unlatching by pulling the handle through the first portion of the travel. But if power fails, the person can unlatch the door manually by continuing to pull the handle through the remaining portion of its travel. This action will move a mechanical linkage that eventually moves the fork bolt detent to allow the fork bolt to rotate to its unlatched position. These latch handles have been used on the inside and outside of the vehicle doors.
One shortcoming with this arrangement arises because the dual action of the unlatching handle (i.e. power and manual) is not as user-friendly as it could be. People operating the handle are not always aware of this dual action, and they tend to pull on the handle with substantial force, expecting that it has only manual action. Of course, only a minimal force is needed in the first portion of the travel, and so the substantial force from the operator is inappropriate. The experience of pulling strongly on a handle that offers no resistance can be mildly jarring and otherwise unsatisfactory for the operator.
Also, this type of latch is impossible to implement in a child security lock situation. Even if one tried to effect the child security feature by cutting electrical power to the rear inside door switch, the child could still manually unlatch the latch by pulling the handle through the remainder of the its travel.
Accordingly, some new arrangement is necessary both to provide a more pleasing action for the operator, and to facilitate the need for a child security lock in connection with power unlatching door latches.
The present invention overcomes the challenges of the prior art by providing an effective and user-friendly way to manually open doors normally unlatched with a power unlatching mechanism when the power fails. The invention is especially useful for manual unlatching of a door whose operation is affected by a child security lock.
According to the invention, the latch handle assembly includes the following basic features. First, there is a support structure adapted to attach to a vehicle door, and a latch handle for manual unlatching of the vehicle door pivotally supported on the support structure between a neutral position and a manual unlatching position. A mechanical linkage is attached to the latch handle and is adapted to interconnect with the door latch for translating motion from the latch handle to the door latch to unlatch the door when the latch handle moves to the unlatching position. The latch handle assembly also includes a switch disposed on the latch handle that is operable to move from a rest position to a power-unlatching position. The switch is adapted to interconnect with the power-assisted unlatching mechanism to allow the switch to unlatch the door when the switch moves to the power-unlatching position. Finally, there is a handle lock disposed adjacent the latch handle. The handle lock is operative to move from a locked position preventing the latch handle from moving to the manual unlatching position, and an unlocked position allowing movement of the latch handle to the manual unlatching position.